Mr Collins, the chairman of the Department for Culture Media and Sport select committee, said: "Given the extraordinary evidence that we've heard so far today... it is absolutely astonishing that Mark Zuckerberg is not prepared to submit himself to questioning.

"These are questions of a fundamental importance and concern to Facebook users, as well as to our inquiry as well.

"I would certainly urge him to think again if he has any care for people that use his company's services."

Facebook said Mr Cox was "well placed to answer the committee's questions".

At the weekend Mr Zuckerberg took out full-page advertisements in several UK and US Sunday newspapers to apologise, adding the company could have done more to stop millions of users having their data exploited by Cambridge Analytica.

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Media captionChristopher Wylie says the company's operations were an example of "modern-day colonialism"

The select committee on Tuesday heard from former Cambridge Analytica employee Christopher Wylie, who claimed the UK may not have voted for Brexit had it not been for "cheating" by the Leave campaign.

Mr Wylie told the committee that Canadian company Aggregate IQ - which has been linked to Cambridge Analytica - received funding from Vote Leave and played a "very significant role" in the referendum result.

He also claimed:

His predecessor died in suspicious circumstances in a hotel in Kenya after a "deal went sour"

Vote Leave and other pro-Brexit groups were working together and had a "common plan" to get round spending controls

Cambridge Analytica worked for Brexit group Leave.EU and its "franchise", Aggregate IQ, was hired by Vote Leave

The data Aggregate IQ possessed was used to target between five and seven million people during the referendum campaign

Aggregate IQ said it had a "conversion rate" of 5-7% in persuading people to vote a specific way

Mr Wylie, whose allegations were first published in the Observer newspaper over a week ago, has accused Cambridge Analytica of gathering the details of 50 million users on Facebook through a personality quiz in 2014.

He alleges that because 270,000 people took the quiz, the data of some 50 million users, mainly in the US, was harvested without their explicit consent via their friend networks.

Mr Wylie claims the data was sold to Cambridge Analytica, which then used it to psychologically profile people and deliver pro-Donald Trump material to them to assist the presidential election campaign.

He described his former boss, Cambridge Analytica's CEO Alexander Nix, as a salesman with no background in politics or technology but a lot of wealth.

On one occasion, the two of them were running late because Mr Nix had to "pick up a £200,000 chandelier", MPs heard.